Bonding of lignocellulosic fiber materials, such as wood fiber, is widely used commercially as for example in the manufacture of paper or fiber products. In present commercial bonding procedures, bonding among the fibers is based primarily on physical forces created by the large surface of finely interlocked cellulose fibers. For increasing the bonding strength of such product, one may add to the pulp, before mat or sheet formation, sizing substances such as starch or resins as adhesives. Strength increase by such procedure is only moderate, and moreover the use thereof increases costs. Strength may also be increased by formation (fibrillation) of longer and more refined fibers. This involves, however, more complicated and costly chemical pulping procedures, and results in lower yield, of about 45% in the Kraft process, compared to 95% in mechanical pulping.